A field sport it's possible to reach by railway (7)
I believe the answer is:
archery
'a field sport' is the definition.
'archery' can be an answer for 'sport' (archery is a kind of sport). I'm not sure about the 'a field' bit.
'possible to reach by railway' is the wordplay.
I cannot really see how this works, but
an anagram of 'reach' is 'arche' which is present in the answer.
'railway' could be 'ry' (abbreviation) and 'ry' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'it's' is the link.
Can you help me to learn more?
(Other definitions for archery that I've seen before include "The sport of bowmen" , "Bowman's sport" , "Arrow-shooting" , "Bowmanship" , "Bow and arrow sport" .)